Gallery: Electronics in the spotlight at Xponential 2016 unmanned systems exhibition

The expanding world of optical sensing

Payloads on UAVs often consist of electro-optical sensors. And as made clear at Xponential technical sessions, there are more kinds of optical sensors than most people think. For example, there are a variety of IR sensor wavelengths. Near infrared (NIR) light includes wavelengths between 700 and 1,100 nm. Water absorbs NIR, so these wavelengths can reveal land-water boundaries that are not obvious in visible light. Shortwave infrared (SWIR) light includes wavelengths between 1,100 and 3,000 nm. Water absorbs shortwave infrared light in three regions: 1,400, 1,900, and 2,400 nm. The more water, the darker the image will appear at these wavelengths. SWIR sensors on drones will penetrate haze better than those used for visible light. Midwave Infrared (MIR) ranges from 3,000 to 5,000 nm. MIR sensors can give clear images in the presence of high humidity. In contrast, thermal or longwave infrared (TIR or LWIR) light includes wavelengths between 8,000 and 15,000 nm. Most of the energy in this part of the spectrum is emitted (not reflected) by the Earth as heat. LWIR sensors don’t image high humidity conditions well at all.